This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A359233 #21 Aug 23 2023 08:42:08
%S A359233 1,1,1,1,2,1,1,1,2,1,2,1,2,1,1,1,3,1,1,2,2,1,2,1,2,1,1,1,4,1,2,1,2,1,
%T A359233 2,1,2,2,1,1,3,2,1,1,3,1,3,1,2,1,1,1,4,1,1,2,2,1,3,1,3,1,1,2,4,1,1,1,
%U A359233 2,1,2,1,3,2,2,1,4,1,1,2,2,1,3,1,2,2,2,1,3,1
%N A359233 Number of divisors of 5*n-1 of form 5*k+1.
%C A359233 Also number of divisors of 5*n-1 of form 5*k+4.
%H A359233 Seiichi Manyama, <a href="/A359233/b359233.txt">Table of n, a(n) for n = 1..10000</a>
%F A359233 a(n) = A001876(5*n-1) = A001899(5*n-1).
%F A359233 G.f.: Sum_{k>0} x^k/(1 - x^(5*k-1)).
%F A359233 G.f.: Sum_{k>0} x^(4*k-3)/(1 - x^(5*k-4)).
%t A359233 a[n_] := DivisorSum[5*n-1, 1 &, Mod[#, 5] == 1 &]; Array[a, 100] (* _Amiram Eldar_, Aug 23 2023 *)
%o A359233 (PARI) a(n) = sumdiv(5*n-1, d, d%5==1);
%o A359233 (PARI) a(n) = sumdiv(5*n-1, d, d%5==4);
%o A359233 (PARI) my(N=100, x='x+O('x^N)); Vec(sum(k=1, N, x^k/(1-x^(5*k-1))))
%o A359233 (PARI) my(N=100, x='x+O('x^N)); Vec(sum(k=1, N, x^(4*k-3)/(1-x^(5*k-4))))
%Y A359233 Cf. A078703, A099774, A359211.
%Y A359233 Cf. A001876, A001899, A359236, A359237, A359238.
%K A359233 nonn,easy
%O A359233 1,5
%A A359233 _Seiichi Manyama_, Dec 22 2022